Our long term goal is to understand the signals that pattern the early vertebrate embryo. We study this problem predominantly in the frog Xenopus laevis. This animal produces large numbers of eggs that are readily manipulated by injection and microsurgery. The combination of experimental embryology and molecular manipulation provide the tools to understand embryonic signaling at the molecular level. Despite the progress that has been made in understanding embryonic signals, there is still only a partial picture of how the detailed pattern of the embryo emerges. The main hypothesis driving work in the next grant period is that there are a substantial number of embryonic signaling activities that remain to be identified. We will identify these signals so that they can be further understood at the embryological and molecular level. In the next grant period, there are three general areas that will be pursued: We will study signals from the neural plate that influence mesodermal and neural fates. We will further dissect the wnt signal transduction pathway that leads to early events of axis formation, and sensitization of the ectoderm to neuralizing signals. Finally, we will use our proven expression cloning techniques to isolate and study molecules that influence mesodermal and neural pattern. Many of the same cellular mechanisms are used in embryos and in adults; therefore an increased understanding of the basic biology of development will improve our understanding of human development and physiology.